1. Field of the Invention
This invention relates to a semiconductor integrated circuit device and an electronic card using the same and more particularly to a countermeasure against destruction caused by charging and discharging operations with respect to the semiconductor integrated circuit device itself.
2. Description of the Related Art
A semiconductor integrated circuit device has a protection circuit and protection function to protect it from an excessively large current supplied to an output terminal thereof. The test standard is defined by MIL (Military. Standards) and EIAJ (Electronic Industries Association of Japan).
A semiconductor integrated circuit device is not used in a singular form and, in general, it is incorporated into an electronic product and used. Therefore, it is considered that the semiconductor integrated circuit device is normally connected to a ground node or power source in the market. In the test standards defined by MIL and EIAJ, a needle is brought into contact with the output terminal to cause an excessively large current to flow into the semiconductor integrated circuit device for a period of time of several tens of nanoseconds to several microseconds. During the test, the semiconductor integrated circuit device is set in a state in which it is connected to the ground node or power source. In this state, the protection circuit and protection function cause the excessively large current in the semiconductor integrated circuit device to leak into the ground node or power source, thus protecting the integrated circuit. As a result, the semiconductor integrated circuit device becomes difficult to be destroyed even if an excessively large current is inadvertently supplied thereto. Thus, the reliability and durability of the electronic product in which the semiconductor integrated circuit device is incorporated are enhanced.
In recent years, the application range of semiconductor integrated circuit devices covers not only electronic products but also various media such as recording media and information media. Conventional recording media and information media are magnetic cards and magnetic disks that magnetically store information. The magnetic storing device replace by a nonvolatile semiconductor memory device. Thus, the information storage amount, information holding characteristics, the degree of information secrecy and the like can be enhanced in comparison with magnetic cards and magnetic disks. Examples of the recording media are called memory cards or IC cards and are widely available on the market. As document which discloses a memory card, for example, document 1 is given. In this specification, all of the recording media and information media utilizing semiconductor integrated circuit devices are called electronic cards.
Document 1: Shigeo Araki, “The Memory Stick”, the web site <hyperlink symbology omitted> pp. 40-46
Like the magnetic card and magnetic disk, the electronic card is not always used while it is incorporated in the electronic product. A person carries the electronic card. That is, the semiconductor integrated circuit device in the electronic card is most frequently set in a state in which it is not electrically connected to the ground node or power source. Further, the conventional protection circuit and protection function cause an excessively large current to leak into the ground node or power source. Therefore, if the semiconductor integrated circuit device is placed in a severe environment while it is connected to neither the ground node nor the power source, there occurs a possibility that the integrated circuit cannot be fully protected by use of a conventional protection circuit and protection function.